At the Hellisheidi Geothermal Plant, high up in Iceland’s western volcanic zone, engineers have found a way to get rid of carbon dioxide pollution: They’re turning it into rock.
The CarbFix project takes CO2, dissolves it in water, and sends it deep beneath the ground, where it reacts with the basalt rock to become calcite. The process could offer a viable option to sequester gases that cause climate change.
In most carbon sequestration projects, the CO2 is compressed into a supercritical liquid and pumped beneath the surface. The gas fills porous rock that lies below layers of impermeable rock, eventually dissolving into the groundwater–but very slowly. With CarbFix, the CO2 starts becoming rock immediately: The engineers claim 95% of the gas becomes stone within two years.
“We’re not storing the CO2 in a gas bubble or something like that in the subsurface. Rather, we are turning it into stone very quickly,” says Edda Aradottir, who manages the project for Reykjavik Energy, one of several partners.
She adds: “We have built infrastructure here in Iceland where we are capturing on an industrial scale. We have designed the method, and it’s easy and automatic, and not that expensive.”
In fact, “not expensive” is relative. CarbFix estimates it can store CO2 at $30 dollars per ton compared to larger-scale projects that report prices double or triple that. But, at the moment, polluters in most countries don’t have to pay anything to release CO2, so every form of storage seems a costly investment (at least without government help).
“That’s part of the problem with the fight against climate change: no-one is obligated yet,” Aradottir says. “But I’m certain that will change after the Paris agreement and everyone is figuring out how to do their part.”
So far, finding viable ways to do “carbon capture and storage” (CCS) have proved elusive. The New York Times recently investigated the $6.4 billion Kemper coal project in Mississippi and found a bevy of cost-overruns and engineering mishaps. Other projects have been slow to come online.
Aradottir doesn’t see CarbFix as a panacea. It, too, needs to be brought to full industrial scale. But it has potential if other engineers can adopt and adapt its ideas. “Our method is not patented so anyone can use it. We’re hoping to see it tried elsewhere, not only in Iceland,” she says.
There’s plenty of basalt around the world including in the Pacific Northwest, Canada, and India. So hopefully we’ll see some experimentation outside Iceland’s geothermal belt soon.
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